An accumulator loading valve of this kind is known from the German patent application published without examination, No. 2,625,555. The two-position pilot valve disclosed there is furnished with an operating piston which is prestressed by a cup spring featuring a diminishing characteristic. This feature alone allows a sudden switch-over between the two potential switching positions. The rapid switch-over of the pilot valve is important for the whole accumulator loading valve since in an undefined intermediate position the accumulator loading function cannot be safeguarded. Cup springs of this kind, with a diminishing characteristic in order to fulfill their function, have a large diameter and, consequently, require a comparatively large housing. Thus, they can reasonably be employed exclusively in hydro-accumulators whose working pressure falls within a medium pressure range (approximately 50 to 60 bar).